Ink-jet printers typically use a mechanical architecture wherein a pen carriage holding one or more print pens, each with a nozzle array, is transported across a stationary print medium to print a swath onto the medium. The medium is advanced between print cycles by a paper advance system to position the medium for subsequent swaths. The paper advance system typically includes a primary drive roller and one or more paper pinching rollers which retain the paper against the drive roller.
There are several disadvantages to this typical mechanical architecture. Transporting the ink-jet pens requires that a volume of space be allocated above the print medium to allow the motion of the carriage and pens. This volume is usually greater than the orthogonal cross-sectional area of the pen multiplied by the medium print width plus two times the pen carriage volume (since the carriage travel through each edge of the medium print width must be taken into account). This volume is typically enclosed, requiring increased part size and cost. Electrical connections to the pen carriage require flexible cables which can survive the repetitive flexing of printing cycles, and require connectors at the main printed circuit assembly mounted to the printer chassis, both of which add to part cost. The moving trailing cable creates an antenna which can lead to electromagnetic radiation interference.